We have achieved our initial goal of collecting >50 billion granulocytes. Using a 9-day stimulation protocol, we were able to collect up to 80 billion cells during apheresis with a mean collection of 65 billion cells. Based on serial measures of blood granulocyte counts, the majority of increases occurred during the last 3 days of the 9-day stimulation. We have also optimized the procedure to maximize cell collection and maintain hematological stability. These improvements will now allow us to determine the efficacy of the therapy in improving survival during severe sepsis.